I'm in the process of building a delta printer. I've gotten to the point where the extruders "work" and the machine responds to the commands I give it. I have an Orion and a rostock max v3 but I really wanted to try and make my own.

I am having some printing issues and was wondering if anyone had any clue what could be happening.

I printed a 20mm cube and ended up with a roughly 12mm cube.

The printer has a Cyclops hotend and I plan on adding a heated bed when I get the rest working.

Was the cube 12mm in all of X, Y and Z? If so, that points to a steps/mm errors, although 80 sounds right for that configuration. If the Z height was 20mm and only X or Y were 12mm, that is an issue with diagonal rod length setting or calibration.

If the belt is off the pulley, mark one tooth with a pen and start counting teeth as you turn the pulley. When you get back to your starting point, you have your count.

If the belt is on the pulley, mark the belt against a fixed reference point. Rotate the pulley exactly one turn (add a mark to the top of the pulley if you need a reference), then make another mark on the belt. Count the teeth on the belt between the two marks.

The pulley teeth and resultant steps will effect your Z height scaling. This is a known quantity based completely on the pulley's circumference, and you should consider a "fixed" number after you calculate and confirm the proper value. The diagonal rod length is the arm length, yes. It's the exact length (center pivot to center pivot) of the arms, and this value will effect your XY scaling.